====== iOS Developer Interview ======


===== Question 1 =====

  * Consider the following code. What's the value of the **len** variable, and why?
  * 参考以下的代码，len的值为何？请解释。

<code>
var array1 = [1, 2, 3, 4, 5]
var array2 = array1
array2.append(6)
var len = array1.count
</code>





===== Question 2 =====

  * Consider the following code. Where is the error and why? How can it be fixed?
  * 参考以下的代码，那里出错了？请解释。如何修复？

<code>
let op1: Int = 1
let op2: UInt = 2
let op3: Double = 3.34
var result = op1 + op2 + op3
</code>


===== Question 3 =====

  * Consider the following code. What is the bug and how does it affect memory? How can it be fixed?
  * 参考以下的代码，那里出错了以及如何影响内存？如何修复？

<code>
class Master {
    lazy var detail: Detail = Detail(master: self)
    
    init() {
        println("Master init")
    }
    
    deinit {
        println("Master deinit")
    }
}

class Detail {
    var master: Master
    
    init(master: Master) {
        println("Detail init")
        self.master = master
    }
    
    deinit {
        println("Detail deinit")
    }
}

func createMaster() {
    var master: Master = Master()
    var detail = master.detail
}
    
createMaster()
</code>



===== Question 4 =====

  * Consider the following **UITableViewCell** constructor. What is the purpose of the **reuseIdentifier**? What is the advantage of setting it to a non-nil value?
  * 参考以下**UITableViewCell**构造数，**reuseIdentifier**的作用是什麽？把它设定为non-nil值有什麽好处？


<code>
init(style: UITableViewCellStyle, reuseIdentifier: String?)
</code>

===== Question 5 =====


  * Write down the log results at 3 different cases
    * Start **MainViewController**
    * Push to **ViewControllerTwo** from **MainViewController**
    * User press back button from **ViewControllerTwo**

  * 我们有以下兩段代码，请分别写下以下三种执行后log的结果
    * 开始 **MainViewController**
    * 從 **MainViewController** 推向 **ViewControllerTwo**
    * 用户在 **ViewControllerTwo** 按back button

<code>
class MainViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        print("MainViewController :", "viewDidLoad")
    }
    
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        print("MainViewController :", "viewWillLayoutSubviews")
    }
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        print("MainViewController :", "viewDidLayoutSubviews")
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print("MainViewController :", "viewWillAppear")
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        print("MainViewController :", "viewDidAppear")
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        print("MainViewController :", "viewWillDisappear")
    }
    
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        print("MainViewController :", "viewDidDisappear")
    }
    
    deinit {
        print("MainViewController :", "deinit")
    }
}
</code>

<code>
class ViewControllerTwo: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        print("ViewControllerTwo :", "viewDidLoad")
    }
    
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        print("ViewControllerTwo :", "viewWillLayoutSubviews")
    }
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        print("ViewControllerTwo :", "viewDidLayoutSubviews")
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print("ViewControllerTwo :", "viewWillAppear")
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        print("ViewControllerTwo :", "viewDidAppear")
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        print("ViewControllerTwo :", "viewWillDisappear")
    }
    
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        print("ViewControllerTwo :", "viewDidDisappear")
    }
    
    deinit {
        print("ViewControllerTwo :", "deinit")
    }
}

</code>